%%%------------------------------------------------------------------------------------------------------------
 \begin{tikzpicture}
\begin{scope}[yscale=0.2,xscale=0.8]
\draw[-,very thick,ublue,domain=-4.2:3.5,samples=100] plot (\x,{ - 1/14 * (\x + 4) * (\x + 1) * (\x - 1) * (\x - 3)});
{
\draw[-,very thick,ugreen,domain=-3.8:3.0,samples=100] plot (\x,{ - 1/14 * (4*\x*\x*\x + 3*\x*\x - 26*\x - 1)});
}
\draw[->,thick] (-6,0) -- (5,0);
\draw[->,thick] (-5,-4) -- (-5,5);

\draw [<-] (-2.5,4) -- (-2,5) node [pos=1,right,inner sep=2pt] {\footnotesize{答案$\tilde{\mathbi{y}}_i$}};
{
\draw [<-] (-3,-3) -- (-2.5,-2) node [pos=0,left,inner sep=2pt] {\footnotesize{预测${\mathbi{y}}_i$}};}

{
\draw [<-] (2.3,1) -- (3.3,2) node [pos=1,right,inner sep=2pt] {\footnotesize{偏差$|\tilde{\mathbi{y}}_i - {\mathbi{y}}_i|$}};
\foreach \x in {-3.8,-3.7,...,3.0}{
    \pgfmathsetmacro{\p}{- 1/14 * (\x + 4) * (\x + 1) * (\x - 1) * (\x - 3)};
    \pgfmathsetmacro{\q}{- 1/14 * (4*\x*\x*\x + 3*\x*\x - 26*\x - 1)};
    \draw [-] (\x,\p) -- (\x, \q);
}
}

\end{scope}
\end{tikzpicture}
%%%------------------------------------------------------------------------------------------------------------
